Abstract: Ensuring the full contact between sinters and cooling gas is the key premise for the utilization of vertical sinter cooling technology. In this study, the gas-solid contact characteristics in a vertical sinter fixed bed have been investigated using a resolved CFD-DEM method. By establishing the sinter DEM model, the sinter packing process in a vertical fixed bed has been simulated. In the coupled calculation, the immersed boundary method and the dynamic mesh refining skill have been used to obtain the fluid flow information around the particles. The results showed that the average voidage of the dual-particle-size uniformly mixed bed was mainly determined by the finer particles, and the larger particles mainly affected the large voidage structure and its distribution. Particle size segregation would increase the average bed voidage, but the voidage distribution would also change largely. Compared with the uniformly mixed bed, the bed with “A type” segregation showed much lower overall pressure drop, but the particles inside the bed did not fully contact with air. The bed with “B type” segregation showed both the features of lower bed pressure drop and desirable gas-solid contact condition. The experimental and simulated bed pressure drops showed very similar trends with the increasing superficial air velocity, which validated the accuracy of the resolved CFD-DEM method.